Suppressor device

ABSTRACT

A suppressor device for an electronic device comprising a plug-in device, comprising at least one plug element, which is arranged on a electrically conducting housing of the electronic device. A printed circuit board is arranged in the housing and bears an electronic circuit leading to the plug element. A capacitor is connected to the plug element and to the potential of the housing. The capacitor is arranged on the printed circuit board which protrudes from the inner part of the housing through an opening with a part thereof and which is also extends from the inner part of the housing to the outer side of the housing. The plug element is conductively connected to the capacitor and the circuit on the part of the printed circuit board located on the outer part of the housing.

PRIORITY CLAIM

This is a U.S. national stage of application No. PCT/DE2003/002031,filed on Jun. 18, 2003. Priority is claimed on the followingapplication(s): Country: Germany, Application No.: 102 33 318.1, Filed:Jul. 22, 2002.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an interference suppression device for anelectronic appliance, the interference suppression device having a plugdevice, with at least one plug element arranged on an electricallyconductive housing of the electronic appliance, a printed circuit boardarranged in the housing and bearing an electrical and/or electroniccircuit to which the plug element is connected, and a capacitorconnected on the one hand to the plug element and on the other hand tothe potential of the housing.

2. Description of the Prior Art

It is known with such interference suppression devices to pass the plugelements of the plug device through cutouts in a plug cover into thehousing interior to connect them there to the capacitor and the circuit.Via the cutouts and metal parts, including the plug elements, whichprotrude into the housing interior from the outside, radio-frequencyinterference radiation of, in particular, >approximately 400 MHz isconducted and irradiated into the interior of the metal housing, whichis actually provided for shielding purposes, and may impair theoperation of the circuit of the electronic appliance owing to thehigh-energy radiation.

SUMMARY OF THE INVENTION

An object of the invention is to provide an interference suppressiondevice which, given a simple and cost-effective design, ensureseffective shielding against, in particular, radio-frequency interferenceradiation and is also suitable for mass production.

This object is achieved according to the invention by an interferencesuspension device for an electronic appliance, including a plug devicewith at least one plug element arranged on an electrically conductivehousing of the electronic appliance, a printed circuit board arranged inthe housing and bearing an electrical and/or electronic circuit to whichthe plug element is connected, and a capacitor connected on the one handto the plug element and on the other hand to the potential of thehousing, the capacitor arranged on the printed circuit board, whereinone part of the printed circuit board protrudes out of the housinginterior of the electronic appliance housing through an opening, and theprinted circuit board extends from the housing interior to a housingexterior. The plug element on that part of the printed circuit boardwhich is located at the housing exterior being conductively connected tothe capacitor and the circuit on the printed circuit board. printedcircuit board which is located in the housing exterior beingconductively connected to the capacitor and the circuit.

This design has the advantage that the interference suppression takesplace even on the outside of the electronic appliance and interferenceradiation does not even reach the housing interior. Such an interferencesuppression device has few components and can therefore be assembled ina simple and cost-effective manner. In this case, without significantadditional complexity, that part of the printed circuit board whichextends from the housing interior to the housing exterior forms,together with the housing having ground potential and in a simplemanner, a bushing capacitor, each individual plug element being filteredeffectively.

Production may be simple if the capacitor comprises a first and a secondcapacitor face which are arranged opposite one another such that theyare separated by an insulating layer, the first capacitor face beingelectrically conductively connected to the potential of the housing, andthe second capacitor face being electrically conductively connected tothe circuit. The insulating layer may be formed in a component-savingmanner by the printed circuit board.

In order to make contact in a simple manner with the housing, the firstcapacitor face may be arranged on the surface of the printed circuitboard.

Particularly effective shielding is achieved if the printed circuitboard has two further capacitor faces, which lie one above the other andwhich are electrically insulated from one another, for the purpose offorming a further capacitor for the same plug element, the thirdcapacitor face being electrically connected to the plug element and thefourth capacitor face being electrically connected to the housingpotential, it being possible in this case too to make contact in asimple manner with the housing if the fourth capacitor face is arrangedon the surface of the printed circuit board.

It goes without saying that, in addition, more than two capacitors mayalso be provided. For this purpose, the printed circuit boards arepreferably multilayer printed circuit boards which may have more thanfour layers on which the capacitor faces are arranged.

If the first and the fourth capacitor faces are conductively connectedto one another by means of plated-through holes which enclose betweenthem the second and the third capacitor faces and preferably extendapproximately on the plane of the housing wall, the second and thirdcapacitor faces are surrounded by ground potential, which leads to areduction in the effective opening cross section and thus to a furtherincrease in the shielding.

For cost-effective production of the capacitor faces, one or more of thecapacitor faces may be capacitor coatings on the printed circuit board.

For signal transmission purposes, the plug element(s) or the capacitorfaces which are conductively connected to the plug elements arepreferably connected to the circuit via signal lines.

In this case, the signal lines can be produced in a simple andcost-effective manner if they are layer lines applied to the printedcircuit board.

In order to increase the shielding effect, the opening in the housingpreferably tightly encloses the printed circuit board passed through it.

A connection to the ground potential is made in a simple manner andwithout significant component complexity if the opening region of thehousing is in conductive contact with a first and/or fourth capacitorface, which is/are arranged on the surface of the printed circuit board.

In this case, no special components are required if the opening regionof the housing bears in a resilient manner against the first and/orfourth capacitor face. At the same time, effective closure of theopening is produced.

Mechanically robust contact is made with the ground potential by theopening region of the housing being connected to the first and/or fourthcapacitor face by a connecting element, in particular by a rivet.

The opening region of the housing may also be connected in aninterlocking manner to the first and/or fourth capacitor face, it beingpossible for this to take place in a simple manner by part of theopening region of the housing being inserted in a corresponding cutoutin the first and/or fourth capacitor face with a press fit.

Both mechanically robust contact is made with the ground potential andclosure of the opening with effective shielding is achieved if theopening region of the housing is conductively connected to the firstand/or fourth capacitor face by adhesive bonding or soldering.

A further connection to the ground potential is achieved if the housingis capacitively coupled to the first and/or fourth capacitor face.

To further increase the shielding effect, the capacitor and/or thefurther capacitor may be connected to the circuit by an interferencesuppression capacitor.

In order to optimize the shielding in the region of the opening furtherstill by reducing the effective opening cross section, the housing wallmay have shielding arms lying adjacent to one another in the region ofthe opening, in which the shielding arms are short in the regions of thecapacitors extending from the housing exterior to the housing interiorand rest with their free ends on the first capacitor face, and theshielding arms are long in the regions free of capacitors extending fromthe housing exterior to the housing interior and extend throughthrough-openings in the printed circuit board until they come to bearwith their free ends against a wall part of the housing.

In this case, contact can be made with the ground potential of thehousing in a simple manner by the shielding arms bearing on the firstcapacitor face and the wall of the housing with resilient prestress.

Production may use few components and may be cost-effective if thehousing wall is in the form of a stamped/bent part in the region of theopening.

For further shielding purposes, that part of the printed circuit boardwhich is located in the housing exterior and capacitors as well as theplug elements can be arranged in an outer, electrically conductivehousing chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention are described in more detailbelow and are illustrated in the drawing, in which:

FIG. 1 is a cross sectional view through a first exemplary embodiment ofan interference suppression device,

FIG. 2 is a plan view of the printed circuit board of the interferencesuppression device shown in FIG. 1,

FIG. 3 is a cross sectional view of the interference suppression deviceshown in FIG. 1 with an illustration of the interference radiation,

FIG. 4 is a cross sectional view through a second exemplary embodimentof an interference suppression device,

FIG. 5 is a cross sectional view through a third exemplary embodiment ofan interference suppression device,

FIG. 6 is a cross sectional view through a fourth exemplary embodimentof an interference suppression device in the region of a short shieldingarm,

FIG. 7 is a cross sectional view through the interference suppressiondevice shown in FIG. 6 in the region of a long shielding arm,

FIG. 8 is a plan view of part of the printed circuit board of theinterference suppression device shown in FIG. 6, and

FIG. 9 is a perspective view of the housing wall in the region of theopening of the interference suppression device shown in FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The interference suppression devices illustrated in the figures have ahousing 1 made of sheet metal for an electronic appliance, which has anopening 3 at a lateral housing wall 2. A printed circuit board 5, whichrests on elevated embossed areas 6 of the base 7 of the housing 1, isarranged in the housing interior 4. The printed circuit board 5 bears anelectronic circuit 33 with which contact can be made from the outsidevia plug elements 8, 8′ and which is fed low-frequency signals via theplug elements 8, 8′.

The printed circuit board 5 has a part 9, which extends through theopening 3 to the housing exterior 10, the base 7 of the housing 1protruding laterally and covering the entire lower region of the printedcircuit board 5, including the part 9.

The plug elements 8, 8′ have plug pins 11, which protrude horizontallyaway from the housing 1 and onto which a corresponding opposing plugpair (not shown) can be plugged. Those ends of the plug elements 8, 8′which are opposite the plug pins 11 protrude vertically through theprinted circuit board 5. The plug element 8 is conductively connected tosecond and third capacitor faces 12 and 13 arranged on the printedcircuit board 5, an insulating layer 32 being arranged between thecapacitor faces 12 and 13. The second and third capacitor faces 12 and13 are connected to one another via a connection 14, and are connectedto the circuit 33 via an interference suppression capacitor 16 and asignal line 15.

The second and third capacitor faces 12 and 13 in this case extend fromthe housing exterior 10 through the opening 3 into the housing interior4. A first capacitor face 18, which forms a capacitor 19 with the secondcapacitor face 12, is arranged on the upper surface of the printedcircuit board 5 such that it lies opposite and parallel to the secondcapacitor face 12 and such that they are separated by an insulatinglayer 17.

In the same manner, a fourth capacitor face 21, which forms a furthercapacitor 22 with the third capacitor face 13, is arranged on the lowersurface of the printed circuit board 5 such that it lies opposite andparallel to the third capacitor face 13 and such that they are separatedby an insulating layer 20.

The figures show the connection of the capacitors 19 and 22 to a plugelement 8. The capacitors associated with the further plug element 8′are located on a sectional plane different to that illustrated.

In exactly the same way as the second and third capacitor faces 12 and13, the first and fourth capacitor faces 18 and 21 also extend from thehousing exterior 10 through the opening 3 into the housing interior 4.In this case, that part 9 of the printed circuit board 5 which extendsthrough the opening 3 is tightly enclosed by the opening 3 in thehousing 1.

In the exemplary embodiments in FIGS. 1, 3, 5, 6 and 7, the fourthcapacitor face 21 rests on the embossed area 6 of the base 7 and is thusconnected to the ground potential of the housing 1.

In the figures, the first capacitor face 18 is connected to the groundpotential of the housing 1 by the housing wall 2 resting on the firstcapacitor face 18 in the region of the opening 3.

In the exemplary embodiment in FIGS. 1 to 3, the housing wall 2 is madeof resilient sheet metal and rests with resilient prestress on a contactregion 25 of the first capacitor face 18.

In FIG. 4, the housing wall 2 is of two-part design in which the housing1 largely covers the plug elements 8, 8′, and said plug elements 8, 8′are surrounded by an inner cover 23 of the housing wall 2 so as to forma housing chamber 24. In this case, the opening 3 is formed at the innercover 23 which is soldered in the opening region to contact regions ofboth the first capacitor face 18 and the fourth capacitor face 21.

In the region in which they touch, the housing wall 2 and the innercover 23 bear against one another in a resilient manner. In theexemplary embodiment in FIG. 5, a housing chamber 24′ is formed by aninner cover 23′ in a similar way to that in FIG. 4. In this case, theinner cover 23′ is soldered at its upper end to the inner wall of thehousing 1 and at its end which rests in a resilient manner on thecontact region of the first capacitor face 18. In the exemplaryembodiment in FIGS. 6 to 9, as in FIG. 5, the housing wall 2 and thus ahousing chamber 24″ is formed by an inner cover 23″. This inner cover23″ in the form of a stamped/bent part made of resilient sheet metal isillustrated as a detail in FIG. 9 and has at its upper end a bent-backsection 26 with which it is riveted to the upper wall of the housing 1.At its end facing the printed circuit board 5, the inner cover 23″ isformed with shielding arms which lie adjacent to one another and whichare alternately short shielding arms 27 and long shielding arms 28.

All of the shielding arms 27 and 28 have a bulge 29 in their centralregion such that they are resilient in their longitudinal extent.

The short shielding arms 27 rest with the end side of their free end ina resilient manner on the contact region 25′ of the first capacitor face18.

Corresponding to the position of the long shielding arms 28,through-openings 30 are formed in the printed circuit board 5, throughwhich through-openings 30 the long shielding arms 28 protrude and, withthe end side of their free ends, bear in a resilient manner against theembossed area 6 of the base 7.

FIGS. 3 to 7 show, by means of arrows 31, the radio-frequencyinterference radiation which is prevented from penetrating into thehousing interior 4 by the interference suppression device.

1. An interference suppression device for an electronic appliance, theelectronic appliance having an electrically conductive housing, saidinterference suppression device comprising: a plug device having atleast one plug element; a printed circuit board having a circuitconnected to said at least one plug element, said printed circuit boardhaving an external portion protruding through an opening in theelectronic appliance housing to an exterior of the electronic appliancehousing and an internal portion extending within an interior of theelectronic appliance housing; and a first capacitor arranged on saidprinted circuit board and connected between said at least one plugelement and a potential of the electronic appliance housing, said atleast plug element being conductively connected to said first capacitorand said circuit at said external portion of said printed circuit board.2. The interference suppression device of claim 1, wherein said firstcapacitor comprises first and second capacitor faces and an insulatinglayer, said first and second capacitor faces being arranged opposite oneanother such that they are separated by said insulating layer, saidfirst capacitor face being conductively connected to the potential ofthe electronic appliance housing, and said second capacitor face beingconductively connected to said circuit.
 3. The interference suppressiondevice of claim 2, wherein said insulating layer is formed by a portionof said printed circuit board.
 4. The interference suppression device ofclaim 2, wherein said first capacitor face is arranged on a surface ofsaid printed circuit board.
 5. The interference suppression device ofclaim 4, wherein said printed circuit board includes a second capacitorincluding third and fourth capacitor faces which lie one above the otherand which are electrically insulated from one another, said thirdcapacitor face being conductively connected to said at least one plugelement and said fourth capacitor face being conductively connected tothe electronic appliance housing potential.
 6. The interferencesuppression device of claim 5, wherein said fourth capacitor face isarranged on a surface of said printed circuit board.
 7. The interferencesuppression device of claim 5, wherein said printed circuit board isarranged and dimensioned so that said first capacitor face isconnectable to the electronic appliance by an interlocking connection.8. The interference suppression device of claim 7, wherein said printedcircuit board defines cutouts arranged and dimensioned for receivingcorresponding portions of the opening region of the electronic appliancehousing with a press fit.
 9. The interference suppression device ofclaim 5, wherein said first and fourth capacitor faces are conductivelyconnected by plated-through holes which enclose between them the secondand the third capacitor faces and extend approximately on the plane ofthe housing wall.
 10. The interference suppression device of claim 5,wherein said printed circuit board is arranged and dimensioned so thatone of said first and fourth capacitor faces is connectable to theelectronic appliance by an interlocking connection.
 11. The interferencesuppression device of claim 10, wherein said printed circuit boarddefines cutouts arranged and dimensioned for receiving correspondingportions of the opening region of the electronic appliance housing witha press fit.
 12. The interference suppression device of claim 5, whereinat least one of said first and fourth capacitor faces is arranged forconductively contacting the electronic appliance housing proximate theopening of the electronic appliance housing.
 13. The interferencesuppression device of claim 12, wherein said at least one of said firstand fourth capacitor faces is arranged such that the electronicappliance housing bears resiliently against said at least one of saidfirst and fourth capacitor faces proximate the opening.
 14. Theinterference suppression device of claim 12, further comprising aconnecting element for connecting said first capacitor face to theopening region of the electronic appliance housing.
 15. The interferencesuppression device of claim 12, further comprising a connecting elementfor connecting said one of said first and fourth capacitor face to theopening region of the electronic appliance housing.
 16. The interferencesuppression device of claim 15, wherein said connecting elementcomprises a rivet.
 17. The interference suppression device of claim 2,wherein at least one of said first and second capacitor faces includes acapacitor coating on the printed circuit board.
 18. The interferencesuppression device of claim 2, wherein said first capacitor face isarranged for conductively contacting the electronic appliance housingproximate the opening of the electronic appliance housing.
 19. Theinterference suppression device of claim 18, wherein said firstcapacitor face is arranged such that the opening region of theelectronic appliance housing bears resiliently against said firstcapacitor face.
 20. The interference suppression device of claim 2,further comprising one of an adhesive bond and solder connection forconductively connecting said first capacitor face to the electronicappliance housing.
 21. The interference suppression device of claim 2,wherein said printed circuit board is dimensioned and arranged such thatsaid printed circuit board is tightly enclosed in the opening in theelectronic appliance housing and said first capacitor face iscapacitively coupled to the electronic appliance housing.
 22. Theinterference suppression device of claim 1, further comprising signallines connecting said circuit to one of said at least one plug elementand said second capacitor face.
 23. The interference suppression deviceof claim 22, wherein said signal lines comprise layer lines applied tosaid printed circuit board.
 24. The interference suppression device ofclaim 1, wherein said printed circuit board is dimensioned and arrangedsuch that said printed circuit board is tightly enclosed in the openingin the electronic appliance housing.
 25. The interference suppressiondevice of claim 1, further comprising an interference suppressioncapacitor, said first capacitor being connected to said circuit by saidinterference suppression capacitor.
 26. The interference suppressiondevice of claim 1, further comprising a housing wall of the electronicappliance housing, said housing wall having shielding arms lyingadjacent to one another in the region of the opening, said shieldingarms comprising short shielding arms in the regions of said firstcapacitor and extending from the housing exterior to the housinginterior, said short shielding arms having free ends resting on saidfirst capacitor face, and said shielding arms further comprising longshielding arms extending in regions free of said first capacitors andextending from the housing exterior to the housing interior throughthrough-openings defined in said printed circuit board, said longshielding arms having free ends bearing against a wall part of thehousing.
 27. The interference suppression device of claim 26, whereinsaid shielding arms bear on said first capacitor face and the wall ofthe housing with resilient prestress.
 28. The interference suppressiondevice of claim 26, wherein said housing wall comprises a stamped andbent part in the region of the opening.
 29. The interference suppressiondevice of claim 1, wherein each of said external portion of said printedcircuit board, said first capacitor and said at least one plug elementare arranged in an outer electrically conductive housing chamber of theelectronic appliance housing separate from the interior of theelectronic appliance housing.